This invention relates to thermoformable, heat cross-linkable PUR rigid foams and to processes for their production and use.
Polyisocyanurate rigid foams suitable for use as interior trim for motor vehicles are already known. Thermoformable polyisocyanurate foams synthesized predominantly from distilled diphenylmethane-4,4'-diisocyanate, for example, are described in DE-OS No. 2,607,380. These foams are economically disadvantageous because almost 80 wt. % is composed of the relatively expensive isocyanate component.
Thermoplastic polyurethane (PUR) foams based on polyesters are described in EP No. 118,876. These foams are technically unsatisfactory for use as interior trim in motor vehicles because they are too flexible. If rigid, self-supporting molded parts are to be obtained, such foams must be reinforced with reactive resin impregnated glass mats. It is only by this additional measure that the necessary dimensional stability under heat can be imparted to the foams.